1. Technical Field
The present invention relates to organic-modified inorganic fine particle producing processes.
2. Related Art
Fine particles of a particle diameter no greater than several micrometers, particularly nanometer-sized particles (nanoparticles) have generated interest as material that exhibits desirable functions, such as in industrial materials (ceramic nanostructure modifying agents, optical functional coating materials, electromagnetic wave shielding materials, secondary battery materials, fluorescence materials, electronic component materials, magnetic recording materials, and polishing materials), and drug and cosmetic materials, and have potential in a wide range of applications, as described in, for example, JP-A-2006-282503.
Practical application of nanoparticles requires adding specific functions to different fine particles. To this end, a technique that can be used to modify the particle surface needs to be established. One such method of adding functions is organic modification, which can be stably used for fine particles, particularly for nanoparticles.
For example, the foregoing patent publication and J. Zhang, et al., ADVANCED MATERIALS, 2007, Vol. 19, No. 2, p. 203-206 describe modifying the surface of inorganic fine particles with an organic group through a supercritical hydrothermal synthesis reaction performed after an aqueous dispersion of an inorganic fine particle precursor in water is introduced into a reaction tube with an organic modifying agent.
Upon testing the methods described in these and other publications by experiments conducted by the present inventors, it was found that the particle diameter has the tendency to coarsely increase in the process of organic modification, and that adjusting only the amount of organic modifying agent added may fail to sufficiently control the particle diameter.